Technical Field
The present application relates to a system for layered construction of a body made of a light-curable substance, comprising a tray made of resilient material for receiving the substance in a liquid or pasty state, a light source for regionally selective curing of the layer of the substance lying on the tray base, and a construction platform arranged above the tray base and capable of being lowered and raised relative thereto for adhering to and lifting the cured substance layer. The present application also relates to a tray for use in a system of this type.
Background Art
A system of the type described in the introduction is known from US 2013/0001834 A1.
The construction of three-dimensional bodies from light-curable substances, such as liquid photo-sensitive synthetic resins or photopolymers, which are irradiated layer by layer by masked or focussed light, is known under a wide range of names, such as rapid prototyping, photo solidification, 3D printing or stereo(litho)graphy. In modern generative production machines, pixel-controllable DLP, MEMS or micromirror chips or controllable lasers are used for the exposure to light of the individual layers and can expose a substance layer resting on a light-permeable baseplate in a single step in order to cure the layer in selected pixel regions. The cured layer adheres to a construction platform held above the baseplate and is then raised with this in order to allow new liquid substance to flow in onto the baseplate, said substance then being cured in a next exposure step, and so on. The body is thus constructed successively from individual layers, whereas the construction platform is raised upwardly successively.
A big problem here is the destruction-free detachment or demoulding of the cured layers from the baseplate so as to allow the next liquid layer to flow in. In the literature, numerous solutions have already been proposed in order to facilitate the demoulding of the cured layer. One of these solutions lies in arranging a transparent, flexible separation film loosely above the baseplate, which film stretches as the platform is raised and then peels off from the last-cured layer, starting from the edge, until it springs back into its original position above the baseplate on account of its resilience (DE 101 19 817 A1, JP H06 246 838 A). Other solutions use a forcibly controlled, pivotable and tippable baseplate having an intermediate resilient separation film (WO 2013/026087 A1, WO 01/05575 A1) or a resilient tray (see US 2013/0001834 A1 mentioned in the introduction), which is tipped downwardly to detach the layers cured in the tray. All of these known solutions have the disadvantage of high pull-off forces of the cured layers from the baseplate, separation film or tray and therefore a reduced robustness of the construction process. Filigree structures thus can be provided only with difficulty. Additional supporting structures are thus usually necessary in the body to be constructed and have to be removed again in a complex manner during final processing and increase the material consumption unnecessarily.